Here in Ky, I was run out of a stream that I'd been fishing by a Cottonmouth...very aggressive...held him off with the tip of my rod till I got to shore...I was wading, fishing for Smallmouth bass.
While I've rarely carried for that specific reason, I do pack a S&W 36 with snake loads while fishing in NC. The rocky gorges that I fish do have Copperheads, and I've killed two in the last ten years or so.
I'm a live and let live guy...the snakes are usually after mice etc. but one that's harboring where kids and other fishermen are tromping around is a menace and needs to be dealt with. The 'snake loads' that I put up use #12 shot over a full dose of Unique or Bullseye and will do the trick out to about ten feet max. I use one 'snake load' per cylinder full, and 125 gr +P's for the rest. Ten feet is plenty of standoff distance, and beats trying to find a good stick to do the job while keeping a wary eye on that bad guy.
Cherish our flag, honor it, defend what it stands for or get the hell out. Our Freedoms are not free, they've been paid for many times over by heros in uniform. Far better men than I, died that we could be FREE.
USAF FAC, 5th Spl Forces, An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73